Recently, number of people who are anxious about their body odor is increasing according to the growing desire for hygiene. The body odor is a collective term for an odor generated from any parts of a body, mainly a head, a mouth, underarms, a genital area, feet or the like. Particularly, since an axillary odor (odor of underarms) is easily sensed by a person oneself or people around, a level thereof, for instance, some factors including the presence, strength, difference in quality or the like of the axillary odor tends to dominate the level of body odor in terms of a whole body. Further, the person oneself or people around often feels the axillary odor itself uncomfortable rather than the body odor.
In the axillary region of a human, there are not only eccrine glands distributed almost all over the body but also peculiar sweat glands called as apocrine glands. The axillary region of a human is a part in which perspiration is less likely to vaporize and bacteria are likely to grow. Hence, it is likely that perspiration secreted from two kinds of sweat glands (eccrine sweat and apocrine sweat), sebum, scurf or the like are metabolized by bacteria on the skin to produce an odor.
An odor due to an eccrine sweat is called as a lower fatty acid odor or simply an acid odor, which is caused by a lower carboxylic acid having 2 to 5 carbons and smells sour and stuffy (hereinafter called as a lower fatty acid odor or an acid odor). Also, such an odor is not only produced in the underarm but also in all skin surfaces of the whole body. On the other hand, an odor derived from the apocrine sweat is produced in an axillary region of a human having so called tragomaschalia habitus and called as an apocrine odor or simply an “axillary odor” to distinguish. The apocrine odor is a pungent odor peculiar to an axillary region and particularly easily sensed by a person oneself or people around. There are individual differences in actual axillary odors, which can be roughly classified into an acid odor, an apocrine odor and the mixed odor thereof.
The people of tragomaschalia habitus tend to have more apocrine glands in the axillary region wherein an acid odor due to an eccrine sweat and an apocrine odor are mixed to produce a strong peculiar odor. Thus, if a person is anxious about own axillary odor, the person tries to reduce the odor by using a deodorant having a deodorant effect or germicidal effect, or by removing apocrine glands of the axillary region in a surgical way if the apocrine odor is particularly strong.
Hence, people who are anxious about own body odor or axillary odor, people who have their body odor pointed out at home, school office or the like by others, or people who may place their underarms in front of someone's face such as hair stylists and dentists even if their odors are in unnoticeable level by themselves have great interest in how much apocrine odor they originally have in their axillary regions, and further whether the use of deodorants or the effort to reduce a body odor such as an operation to remove apocrine glands is currently effective.
Conventionally, as methods of assessing a body odor, particularly an apocrine odor, there are: (1) an organoleptic test wherein a third party smells to determine an odor of perspiration of axillary regions with one's nose; (2) an empirical assessing method which presumes from the facts which are considered to be relative to an apocrine odor such as genetic information, e.g. whether there is a family member having tragomaschalia habit, a wet cerumen, coloring of an underwear in the axillary regions or the like; (3) a method which presumes from number and size of apocrine glands, or the like.
The method (1) needs professional panel members such as a skilled dermatologist, thus, it cannot be easily performed. Also, the method (1) assesses the level of apocrine odor by smelling an odor of the cotton wool which wiped underarms of a test subject, which allows to mingle a judgment with a large degree of the assessor's subjectivity and has difficulty in a quantitative evaluation. Further, when the evaluation is performed consecutively, a sense of smell may get tired so as to lower objectivity.
The method (2) judges from genetic potential or indirectly judges from a relationship between a wet cerumen and an apocrine odor. The assessment by coloring of underwear focuses on coloring matter contained in perspiration of apocrine glands, which does not directly evaluate the apocrine odor of axillary regions, thus, it is an indirect assessment method.
Therefore, there is a risk of false assessment with limited evaluation points and there is a possibility of ignoring axillary odor which is not actualized. Also, such studies can be rough indications for assessing tragomaschalia habit, however, since they are not quantitative and hard to assess, they may lack accuracy and be not practical to assess the improvement in axillary odor after the operation to remove apocrine glands, the presence and level of recurrence of apocrine odor due to regeneration of apocrine glands after the operation, the effectiveness of deodorizing or masking of a deodorant or the like.
The method (3) estimates a level of a body odor in such manner that a doctor makes a surgical incision in axillary regions and then observes number and size of apocrine glands. A test subject needs to accept mental and physical suffering, thus, the method cannot be easily performed. Also, the operation fee is generally high.
Trans-3-methyl-2-hexenoic acid, 7-octenoic acid or the like contained in perspiration of underarms as odor components which are distinctive of underarms is disclosed in “Molecular Recognition of Taste and Smell,” Kagaku Sosetsu No. 40, 205-211, (1999). An use of certain β-hydroxycarboxylic acid or the salt thereof as an animal perfume material is disclosed in Japanese Patent Application Laid-Open (JP-A) No. Hei. 10-25265.
On the other hand, a compound having a thiol group at the 3-position which has an effect to provide a significantly strong clary sage-like odor as a flavoring component is disclosed in JP-A No. 2000-95753.
3-Mercapto-3-methyl-hexane-1-ol and 3-mercapto-2-methyl-butane-1-ol are disclosed as alcohol compounds having a mercapto group at the 3-position in JP-A No. 2001-2634. They are disclosed as flavoring components having characteristics, wherein a S isomer of 3-mercapto-3-methyl-hexane-1-ol has a grass-like or, agrestic odor, a R isomer of 3-mercapto-3-methyl-hexane-1-ol has a grapefruit/passion fruit-like, currant-like or onion-like odor, and 3-mercapto-2-methyl-butane-1-ol has a grass-like, leek-like and gas-like odor.
3-Mercapto alcohol and formic and acetic esters thereof are disclosed in German Patent Application Laid-Open No. 2,316,456 as fragrance agents and flavor agents effective for preparation and modification of a wide range of flavor components, wherein said 3-mercapto alcohol and formic and acetic esters thereof have onion-like, sulfur-like or sweat-like odor.
A thio derivative used as a flavor component and/or a flavor enhancer is disclosed in JP-A No. 2003-12637, wherein the thio derivative reminds of smell of a blackcurrant, onion or grapefruit.
However, none of β-hydroxycarboxylic acid and/or derivative thereof and the alcohol compounds having a mercapto group at the 3-position and/or derivatives thereof was recognized to have a relationship with a body odor of a human particularly in terms of a causative agent of a body odor or a constituent of an axillary odor of a human. Hence, presence or strength of a body odor of a human, particularly, an apocrine odor of axillary regions has not been able to be assessed objectively and quantitatively.
Also, as a characteristic component of the apocrine odor in axillary regions of a human, there were conventionally not only unsaturated carboxylic acid having 6 to 10 carbons as typified by trans-3-methyl-2-hexenoic acid and 7-octenoic acid but also lower carboxylic acid having 5 or less carbons which causes acid odor and higher carboxylic acid originated from sebum in mixture. It has been difficult to selectively separate the unsaturated carboxylic acid which is a characteristic component of an apocrine odor among the various acid components